At the beginning of this month I noticed something very disturbing.
I got a happy new month message from a dear friend and I tried replying; no way. I tried repeatedly, I kept getting message not sent. I googled the MTN SMSC code and as expected it was still +2348030000000, I tapped that into my modded android phone and got an error. I googled all the combination of mtn + android + sms + message + error + can't send; and no suggestion found worked. I switched the phone off and on severally, no result.
So for more than 8 days I couldn't send an SMS.
Then suddenly, on Wednesday, like a flash bulb, an idea lit up in my head. I removed my Airtel SIM from my Blackberry and put the SIM in the android phone, then I went to the settings to see the SMSC number. To my surprise it was 089132420000000f8 instead of +2348020000000 that is the actual SMSC number. I tried sending an SMS and it was successful.
So I did what anyone would do.
Airtel's real SMSC number is +2348020000000 but my android phone sees it as 089132420000000f8
Then MTN's that is +2348030000000 must be same as 089132430000000f8 on my android phone.
I removed the Airtel SIM and put back in my MTN SIM, updated the SMSC number as 089132430000000f8 and that was it! I was able to send SMSs again!
So, if you ever get into similar problem. Forget about what the SIM manual says and take the SMSC numbers to be -
089132420000000f8 for Airtel, and
089132430000000f8 for MTN
And if you can't seem to find where to enter this setting, dial #*#*4636#*#* and you'll be taken to Android secret settings menu. In the Phone Information, scroll down and you'll see the SMSC field. Enter the SMSC number and tap on Update.
Need extra help, ask via the comment box.